Pendant -The pendant gives the operator precise control over the motions of the crane. There are many configurations of pendant depending on the functions of the equipment being controlled. Each pushbutton on the pendent controls an operating function of the crane.
The pendant may be suspended from the Trolley Hoist, requiring the operator to walk with and beside the load, or on a separate sliding track system allowing the operator to move independently of the load.
VFD - A pendant can also be used in conjunction with a Variable Frequency Drive. A VFD is used to vary the frequency of the motors controlling the motions allowing for smooth acceleration and deceleration. The buttons on the pendant operate a VFD unit operated in much the same way as Two Speed control. The first step is held to maintain the current speed while the second step is used for acceleration. Deceleration is achieved by releasing the button entirely. Pressing the button back to the first step will maintain the new slower speed. It should be noted that the deceleration is not achieved through uncontrolled coasting but through a programmable dynamic braking system. The control provided by a VFD allows for a high level of customization.
Radio Control -The radio control performs exactly like the pendant but operates using a radio frequency. The radio control incorporates numerous safety features and allows the operator a greater range of operator motion than a pendant.
Power Supply - The electrical service available in the building for which the crane is being designed (i.e. 575 Volt, 3 Phase, 60 Hertz).
Enclosures -The enclosures house all of the electrical components on the crane and are rated by the National Electrical Manufacturers Association (NEMA) or the Canadian Electrical Manufacturers Association (CEMA) as to the level of protection they provide from the conditions in the surrounding environment. There are three basic levels of protection.
CEMA/NEMA 1 - Provides protection against accidental contact with, and electrical shock from, enclosed equipment.
CEMA/NEMA 12 - Provides indoor protection against falling dirt, dust, oil and water.
CEMA/NEMA 4 -Provides indoor protection in hosed down, very wet or outdoor environments, as well as falling dirt, dust, oil and water.